Abstract
Objective. To evaluate and quantify the effect of inferior oblique muscle weakening on horizontal deviations. Methods. The medical files of patients who had undergone an inferior oblique weakening as a single procedure were all reviewed. The main measures were the type of inferior oblique overaction (IOOA), pre- and postoperative amount of IOOA, and horizontal deviations in primary position. Results. The study was conducted with 66 patients (30 males, 36 females). The median age was 11 years (1–49). Of the 66 patients, 30 (45.5%) had primary and 36 (54.5%) had secondary IOOA. The most common procedure was inferior oblique anteriorization in 32 patients (48.5%). The mean postoperative horizontal and vertical deviations and the amount of IOOA were decreased postoperatively (p = 0.001 for all). The median amount of correction of horizontal near and distance deviations was 4Δ (0–20). The preoperative amount of IOOA, the presence of fourth nerve palsy, and the type of the weakening procedure had no significant effect on the amount of correction of horizontal deviations. Conclusion. The inferior oblique weakening procedures have secondary effects and warrant reduction of horizontal deviations in varying degrees. This should be borne in mind in planning a simultaneous horizontal muscle surgery and setting the surgical amount.
Highlights
Inferior oblique muscle overaction (IOOA) may be primary or secondary. The former occurs in 72% of congenital esotropia, 34% of accommodative esotropia, and 32% of intermittent exotropia [1]
There is a possibility that inferior oblique weakening may affect by itself horizontal alignment in primary position, may influence plans and numbers of horizontal muscle surgeries, and it may be enough in a particular amount of deviations to provide horizontal alignment without need for additional horizontal surgeries
The intention of the present study was to evaluate the effect of inferior oblique muscle weakening on horizontal deviation in primary position and to empirically determine the relationship between the type of the procedure and the amount of the effect if there was any and to be able to predict the horizontal aligning effect
Summary
Inferior oblique muscle overaction (IOOA) may be primary or secondary. The former occurs in 72% of congenital esotropia, 34% of accommodative esotropia, and 32% of intermittent exotropia [1]. A variety of procedures have been performed including recession, hang-back recession, myotomy, myectomy, anterior transposition, nasal transposition, denervation, and muscle fixation [2,3,4,5,6,7]. These surgeries may have effect on vertical deviations and on horizontal deviations in varying degrees. The intention of the present study was to evaluate the effect of inferior oblique muscle weakening on horizontal deviation in primary position and to empirically determine the relationship between the type of the procedure and the amount of the effect if there was any and to be able to predict the horizontal aligning effect
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